ATM communication system with a modular structure serve for the connection of communication terminals with high transmission rates in private and public communication networks. The transmission and switching of the messages take place using the Asynchronous Transfer Mode, in which the information items to be transmitted are transmitted and switched in packet form, i.e. with packets of fixed length (cells) in accordance with CCITT standard I.361. Internationally standardized transport bit rates are currently 155 and 622 Mbit/s. With the aid of channel and path information inserted in the cell headers of the cells, the cells are transmitted over a virtual transmission channel from one communication terminal via a communication system to a particular communication terminal. The transmission channel is set up by signaling from a subscriber--as in the known time-division multiplex communication systems--or by an administrative input at the communication system and is logically retained for the duration of the connection. The bandwidth of such a transmission channel is flexible and is applied for when the connection is established. Such basic functions of ATM communication systems are known from the publication "ATM Technologie fur zukunftige Breitbandnetze" ATM Technology for Future Broadband Networks!, Siemens, 1992.
A structure of an ATM communication system having such functions is known from telcom report 13, "Mit ATM zur bitvariablen Kommunikation" With ATM to Bit-Variable Communication!, 1990, pages 4-7. In the case of this structure, the ATM communication system or the ATM switching device is formed by a line trunk group having subscriber line modules, by an ATM switching matrix and by a central controller, the central controller being connected directly to the subscriber line modules for a transmission of switching, operation and dependability information. In this concept, a modification of the configuration of the communication system involves considerable hardware and software modifications.
A further ATM communication system for the switching of packeted cells between ATM communication terminals over dial-up or fixed connections is known from the publication IEEE IN HOUSTON GLOBECOM '93 . . . . In this system, there are a plurality of subscriber line modules which are equipped with SDH subscriber interfaces and are known as "Line Cards" connected to an ATM switching matrix, which is provided with a plurality of bidirectional terminal connections and operates by ATM, in each case via a multiplexer/demultiplexer stage referred to as a "Fabric Interface". It is also the case with this concept that, in particular, configuration modifications to the switching software bring about considerable hardware and software modifications.
Furthermore, in European Patent Specification EP-A2 0 358 597 there is described a modular communication system having a switching device and having a personal computer realizing a control device, there being integrated in the switching device a switching matrix of which the terminal connections are connected to subscriber line modules. Both in the switching device and in the control device there are defined corresponding interfaces, which permit an exchange of information or data between the two units. The control device according to the disclosed arrangement serves for expanding an existing switching device by adding any desired additional features, while ensuring the necessary operational dependability. Consequently, software modifications, in particular to the switching software, in the switching device likewise cause software modifications in the control device.